I see some professional DD gamers switch from one god to another in the middle of a game. This is something many casual players don't do, as far as I think, being a casual player myself. Puzzles introducing god switching could be a good introduction for them to do that in real games.
To me, if a puzzle would encourage you to do something new in a secluded area, like a new strategy or something, which makes you say "Hey, I didn't think of that. Let's try that one in a real game!" are good puzzles.
Other examples are:
- Leveling in a mid-fight.
- Using CYDSTEPP, recovering 10 mana, fight till death (with death protection), using CYDSTEPP again, then kill the enemy.
- Using CYDSTEPP, recovering 13 mana, fight till death (with death protection), using CYDSTEPP again, using GETINDARE, first-strike kill the enemy.
- How to use APHEELSIK effective.
- How to use BLUDTOPOWA effective.
- An end-of-chapter exam, using all techniques learned through the whole puzzle chapter.
- Effective use of level catapult (or whatever it was called).
- You can only borrow so many items. Most of them are filled with items. To use new items, you have to convert older ones. But which ones? And when exactly...? (e.g. if you have 70/80 conversion points. Convert an item into 10 conversion points and receive 2 health potions (as a halfling). Do you want to convert it when you have full health? Then you can't use them and still can't pick up that new item (since health potions take in a slot of your inventory, even without another potion type).)